Suketu Mehta is tucking into a vegetarian lunch in one of his favourite Thai restaurants in New York’s Jackson Heights district and looking back in – and on – the anger of 2017. His anger was the result of journalistic assignments to Hungary where he witnessedpolitically choreographed rage against north African refugees crossing the border from Serbia. Back in America, itself dinning with nationalistic bloviation, his Foreign Policy magazine article on what he now calls “the whole staggering hypocrisy of the global debate around migration” resulted in hundreds of threatening tweets and emails. “Essentially what I said was that people are coming to rich countries from poor countries not because they want to, but because rich countries had stolen the futures of poor countries.”

Mehta himself is an immigrant. Born in Calcutta in 1963, he moved with his Gujarati parents to Jackson Heights in 1977. “Fourteen is a strange age at which to shift countries, because you never finished growing up in one and you never fully wear the skin in the one you move to,” he reflects. He attended a Catholic school where “I was kicked out of the speech and debate team because of my accent.” He was beaten up more than once. Yet this predominantly working-class area, rich in teeming, noisy sidewalks, is still close to his heart.

I’m always shocked by the lack of historical awareness of the average American. Many people who have come here did so to forget history

Mehta leads me through Jackson Heights – botánicas selling spiritual and occult fare, illegal basement residences, strip clubs, a street sign honouring Alfred Butts, the local who devised Scrabble in 1931. Like that board game, Mehta is intrigued by fashioning sense from what initially seems like nonsense. His first and widely heralded book Maximum City, a 2005 Pulitzer finalist, was a collagist portrait of Mumbai, a place often characterised by cultural tourists as unlivable and chaotic. At more than 600 pages long it was vivid, multi-accented, brimming with tales of hitmen, sex workers and crooked politicians. The novelist Amit Chaudhuri praised it for its “giant embrace not only of a city but of hope – and its more complex, early incarnation, desire – in the age of the free market”. Rather than being an earnest sociology of a “Third World megalopolis” or focusing solely on structural problems, it evoked possibilities. Its enduring value lay in the extent to which it made it difficult for writers to dismiss cities in reductive language, using terms such as slums, ghettoes and favelas.

This Land Is Our Land: An Immigrant’s Manifesto, published this month in the UK, is a different kind of book that toggles between journalistic dispatch, memoir, postcolonial critique and vigorous polemic of the existential guile and social vitality that immigrants possess. It’s also animated by a rage at what he believes is the hypocrisy of the west, sardonically drawing attention in its opening pages to the way in which “they fouled the air above us and the waters around us, making our farms barren, our oceans lifeless; and they were aghast when the poorest among us arrived at their borders, not to steal but to work, to clean their shit, and to fuck their men”.

Mehta holds American citizenship and is an associate professor of journalism at New York University. Who are “they” I ask. “I am a migrant, but I’m also an American. My taxes financed an illegal and incredibly bloody war that plunged the whole of the Middle East into turmoil. I’m the recipient of an economy that is fouling the atmosphere. So I’m certainly enjoying my privilege here and deeply implicated in all of this. Yet I’m always shocked by the lack of historical awareness on the part of the average American. Many of the people who have come here did so to forget history, to turn their backs on history.”

Mehta’s parents expected him to go into the diamond business and were less than happy when he decided to become a journalist. “They had an immigrant fear that I wouldn’t be able to support my family. And for a long time I didn’t. I wrote for technical magazines. I lived in the East Village and had to pay the rent with credit cards. I lived in a Brooklyn studio rife with bed bugs.”

A formative experience was an assignment for the Village Voice on the 1984 Union Carbide gas disaster in Bhopal. “I saw the way a multinational could go into India, cut safety mechanisms at the plant to save money, and then, when the plant blew up killing tens of thousands of people – I met people who had lost their entire families that night – it paid token compensation, $200. And because it’s a multinational it just severs a limb, shuts down Union Carbide India, and then grows another limb somewhere else.”

I was standing at the border with my reporter’s notebook, trying to harvest stories, and I broke down weeping

Mehta sees the extractive practices of contemporary capitalism as a form of neo-colonialism. “The biggest reason for mass migration is the astonishingly obtuse mapmaking of the colonial powers. Just two countries – Britain and France – made 40% of the colonial borders. When Britain left India after two centuries of rule they brought in a gormless barrister, Cyril Radcliffe, who’d never been to India, and gave him six weeks to draw two lines down a map, which now form the dividing lines between 1.6 billion people and have ensured permanent conflict between the two countries.”

One of the most memorable scenes in This Land Is Our Land comes early on when Mehta visits a tiny stretch of ground known as Friendship Park. Lying between San Diego and Tijuana, it is the only place along the 2,000-mile US-Mexican border where families can meet – albeit across a wire fence. If a child wanted to touch her mother, Mehta writes, “she could stick her pinky inside the fence, and her mother could do the same on the opposite side, and the tips of their pinkies could touch: the dance of the fingers, the ‘pinky kiss’”.

It is a beautiful, terrible detail that cuts through all slogans and pieties to isolate the cruelty of modern-day partition. “I broke down weeping at Friendship Park,” Mehta recalls. “I was standing there with my reporter’s notebook trying to harvest stories. This man, this taciturn Mexican who hadn’t seen his mother for 17 years, rode up to the fence. And then mama comes along. And … he can’t hug her. I mean, what do you say? She asks if he’s eating right. Of course he breaks down …

Mehta also remembers a brother and sister meeting their parents there. “They blamed their parents for abandoning them and moving back to Mexico. They hadn’t seen their parents for 11 years and they said to me, ‘We fight but … this is love … This is what we’ve been missing.’ I ran to my car and I was weeping and I called my parents in New Jersey and told them how much I loved them. They don’t get these kinds of calls from me.

“We talk about family values. In Friendship Park you see people trying to touch each other in the most basic of ways. The need of the human body for touch. And … they’re not allowed to hug because some horrible bureaucrat has decided that hugging might be a national security threat. The border patrol chief there told me that God evicted Adam and Eve from the Garden of Eden and built a wall around it …”

Though he’s most closely associated with Mumbai (a place he still thinks of as Bombay), Mehta has spent stretches of his life in other cities, among them Paris, São Paulo and London. “I remember walking down a shopping street in Milford [in Surrey] and a group of white yobs yelling out ‘Paki’. I think the South Asians in the country were much more ghetto-ised. They weren’t even pretending to be British. They had a very strong identification with London but not with being British. Whereas most of the people in this restaurant can aspire to American-ness.”

Would he urge 14-year-olds growing up in modern-day Gujarat to migrate to the US? “No. The 20th century used to be the American century. The 21st century not so much. There are going to be more and more Americans moving out. There are already 9 million non-military Americans living outside the US. The biggest factor is healthcare: every time I go to Europe I meet expats who say: ‘We don’t have to worry about getting sick here.’ It’s really interesting to hear Americans in Europe or in India grouse about the immigration system and having to stand in line to get their visas renewed. There’s a rich justice to that.”

Mehta says he’s “deeply enraged” not just by the nationalistic harrumphing of politicians such as Donald Trump, Boris Johnson and Nigel Farage, but by more “mainstream” commentators such as Thomas Friedman and Andrew Sullivan. He hopes to offer a “counterargument backed up by footnotes” and is spoiling for a fight. “I’m hoping to get on Fox News – on Tucker Carlson and Laura Ingram – and to get into the belly of the beast.”

Trump is excellent at speaking in parables. And that’s how Jesus and prophets and religious leaders throughout history spoke

Does anyone care about footnotes? Is truth itself overrated? “I’m not a politician,” he admits. “I’m not a demographer or an economist. I come from a storytelling tradition – the diamond world – where I grew up listening to my father, grandfather and uncle telling wonderful mercantile stories of people they had met in business who had tried to cheat them – and who they had cheated.

“The whole debate around migration is populist and the populists are gifted storytellers. They can tell a false story well. Trump is excellent at speaking in parables. And that’s how Jesus and all prophets and religious leaders throughout history spoke: in parables. There’s nothing in the Bible that says 86% of people in a recent poll believe you should do unto your neighbour as he does to you.”

Mehta often comes across as wistful for the freedom of fiction writing. He has an MFA from the Iowa Writers’ Workshop (“If you change one letter it becomes the Iowa Waiters Workshop – an appellation far more indicative of the eventual fate of its graduates,” he laughs), and earlier in his career was published in the O Henry award anthology of short stories. “If I want to read about 19th-century Russia, I don’t read the newspapers; I read Tolstoy or Chekhov. The idea of not being bound to the tyranny of facts, to have the licence to go inside the heads of your characters, to not have a message, to write an anti-manifesto: there’s so much more you can say in fiction.”

Does that make it tricky to teach journalism? “On the first day of class I take them on to the Staten Island ferry, and as we approach Manhattan I have them all read out the Walt Whitman poem ‘Crossing Brooklyn Ferry’. I tell them if they can have his attention to detail as well as marshal a larger argument then they will be crackerjack journalists. To be a better journalist read more poetry! I don’t believe in church and state separations between different genres. I collect stories, I assemble stories, I tell stories: whether they come out as real or invented is secondary. These days people stick to their lanes – and I’ve never stuck to any lanes.”

•This Land Is Our Land: An Immigrant’s Manifesto by Suketu Mehta is published by Jonathan Cape (RRP £14.99). To order a copy go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £15, online orders only. Phone orders min p&p of £1.99.